Radio apparatus



cs. 0. WILMS 1,737,903

RADIO APPARATUS Dec. 3, 1929.

Original Filed April 3. 1922 2 Sheets-Sheet 1 'Dec. 3, 1929. cs. 0.WILMS 1,737,903

RADIO APPARATUS Original Filed April 3, 1922 2 s t -s t 2 Patented Dec.'3, 1929 GGNSIN TO THE RELIANGE COMPANY, OF MILWAUKEE, WISCONSEN, C0335?'lIQE-F nick-4 Gontlnuation of appiicatien serial lto. 549,352, filedaprii 52, 19552.

fierial. Ho. 57%,802.

This application is a continuation of application Serial No. 549,352,filed April 3, 1922, as to matter common to both applica tions.

The invention relates to radio apparatus.

The radio apparatus to which the invention applies in particular has anelectronic valve or tube and a rheostat for regulating the same.

An electronic valve is very sensitive and an infinitesimal variation ofthe resistance in any circuit thereof causes a pronounced change in theaction of the valve.

If an electronic valve in a radio receiver is controlled by a rheostatwhich has infinitesimal irregularities in the variations of itsresistance, the receiver will produce objectionable noises and bedifficult to adjust.

An object of the'invention is to obtain a smooth and regular variationin the action" ofelectronic valves employed in radio apparatus.

Another object is to provide radio apparatus in which the resistance ina valve circuit may be gradually and uniformly varied.

According to the invention, a carbon disc resistor is connected incircuit with the electronic valve and has the pressure thereon varied bya low tension spring which is controlled by an actuator and proportionedto vary a low pressure upon the resistor and cause a gradual and uniformvariation in the resistance thereof through a wide working range. I

Applications of the invention are shown in the accompanying drawing inwhich'the views are as follows:

Fig. 1 is a diagram of a radio receiver showing the regulating rheostatconnected in circuit with the cathode of an electronic valve which isemployed as a detector.

Fig. 2 is a diagram showing the regulating rheostat connected in circuitwith the supplemental anode of an electronic valve.

Fig. 3 is a diagram showing the regulating rheostat connected in circuitwith the cathode and the anode of an electronic valve.

Fig. 4 is a section through the rheostat shown in Figs. 1 and 3.

Fig. 5 shows comparative curves illustrat- Rcnewed April 10, it

Ellis application tied Eels? 1S,

ing the characteristics oi the regulating rhee= stat and priorrheostats.

Fig. 1 will first be described. it shows a radio telephone receivingsystem in which telephone receivers 1 are connected te a grounded aerial2 by a transformer and rent supplied from battery 9, or other source,

the amount of current being regulated by a rheostat 10.

The telephone receivers 1 are connected in series with a battery 11between the cathode 6 and the anode 7. Battery 11 maintains the anode 7at positive potential with respect to the cathode 6.

The supplemental anode 8 is connected to one terminal of the secondaryof transformer 3, the other terminal of which is connected to thecathode 6.

A condenser 12 of low capacity shunted by a hlgh resistance 13 may beconnected between the transformer 3 and the electronic valve 4:. Thetelephone receivers 1 may have a condenser 14: connected in paralleltherewith. v

The rheostat 1.0 is employed to vary the resistance in circuit withbattery9 so as to vary the current supplied to the cathode 6 and thusvary the temperature thereof.

The regulating rheostat may be located in the grid circuit of theelectronic valve as shown in Fig. 2 or in the plate circuit as shown inFig. 3.

The regulating rheostat which is a pressure rheostat comprises ingeneral, resistors 20 and an actuator 21 for compressing anddecompressing the same to vary the resistance thereof.

Each resistor is made of a plurality of contacting electrodes 22 ofgraphite or other suitable material. The electrodes may take the form offiat disks.

Each end disk 23 is thicker than the intermediate disks and may be madeof metal silver plated to insure good electrical contact withco-operating parts.

The resistors are located in spaced pockets of an insulating casing 24made of porcelain or other suitable material ordinarily held in v theposition shown in Fig. 4.

The inner end disk 23 of each resistor is in contact with the head of ahollow rivet 25 by which terminals 26 are fastened to the casing 24. Therivets 25 also fasten to the casing contact springs 27 which whenelectrically connected short circuit the resistors.

The actuator 21 comprises a micrometric screw 28 mounted on a rotatablespindle 29. The screw 28 is threaded into a nut 30 fastened to thecasing cover 31.

The inner conical end 32 of the spindle 29 fits in the conical recess 33in the outer end of a guide pin 34, the inner end of which is located inan aperture 35 in the casing.

The angle of the conical end 32 is less than that of the conical recess33 so as to reduce the contacting surfaces thereof and allow the conicalend to seat properly in the recess.

The guide pin 34 carries a bridging contact spring 36 loosely seatedagainst a shoulder formed on the guide pin.

The guide pin 34 and the bridging contact spring 36 are adapted to bemoved inwardly against a spring 37.

The outer ends of the bridging contact spring 36 are adapted to engagethe outer end disks 23 and thereby connect the resistors in series.

The bridging contact spring 36 may be silver plated to insure goodelectrical contact with the end disks.

The bridging contact spring 36 due .to its resiliency absorbsirregularities in pressure due to anyirregular movement of the actuator,and enables the resistance to be varied steadily and smoothly.

The spring 37 tends at all times to force the bridging contact spring 36out of contact with the end electrodes of the resistors. Thus when theactuator is at the outer limit of its movement the bridging contactspring 36 is forced out of contact with the end electrodes.

The spring 37 also assists the bridging contact spring 36 in absorbingirregularities in pressure due to any irregular movement of theactuator.

A shoulder 38 on the guide pin 34 engages the base of the casing thuslimiting the inward movement of the guide pin and the compression of theresistors.

The outer end of the spindle 29 is provided with a knob 39 by which themicro screw is threaded through the nut.

The inward movement of the actuator and ide pin causes the outer ends ofthe bridgmg contact spring to engage the end disks of the resistors andcompress the resistors t0 decrease the resistance thereof.

. Movement in the opposite direction decompresses the resistors toincrease the resistancethereof.

When at the limit of its outward movement the bridgin contact spring isout of contact with the en disks.

The electrodes of the resistors are thus relieved of pressure, and thecircuit between the resistors-is opened.

When the guide p1n 34 is at the limit of its inward movement it engagescontact springsv 27 thus short circuiting the resistors and removing thesame from circuit.

The comcal connection between the s indle and guide pin. co-operateswith the bridging contact spring to equalize the pressure on the tworesistors.

The cover 31 may be fastened to the casing 24 by rivets 40 or otherfastening means.

The cover 31 is provided with mounting lugs '41 by which the rheostat isfastened to a panel 42 or other support so the resistors will occupy theosition shown in Fig. 4.

The angle of t e threads of the micrometric screw actuator isapproximately 137.

The axial movement of the actuator is less each complete turn thereof.

steadily, smooth y and accurately throughout the range required for theregulation of the valve and obtain very accurate and sharp tuning of thecircuits of the radio telephone receiving circuits wherein the radioapparatus is employed.

Of course, other forms of the pressure regulating rheostat such asareshown in my coending application Serial No. 574,803 filed uly 13, 1922,may be em loyed in the same manner as'that disclosed herein.

Fig. 5 shows resistance curves of the pressure rheostat and wirerheostats. The ordinates represent resistance and the abscissa movementof the actuator.

Curve A- illustrates the smooth and steady than twenty-five thousandthsof an inch for variation of the resistance of the pressure rheostat.

Curve B illustrates the variation in resistance of a step-by-step wirerheostat.

Curve C illustrates the variation in resist ance of a vernierstep-by-step wire rheostat.

, A ste -by-step wire rheostat is irregular in action ue to many causesamong which are variations in pressure between contacts and changesbetween values of resistances.

The irregularities are uncontrollable. Therefore when employed toregulate an electronic valve employed in a radio telephone system, theirregular action of the valve results, causing the telephonereceiver toproduce objectionable noises and disturbances.

While in some instances the irregularities in resistance may not'begreat in themselves, they are greatly magnified by the electronic valvewhich it regulates so that objectionable noises and disturbances areproduced by the telephone receiver.

All such objectionable noises and disturbances seriously interfere withthe tuning of the apparatus of the receiving system.

An inspection of the curves of Fig. 5 readily shows that the radioapparatus wherein are combined an electronic valve and the pressureregulating rheostat overcomes the objectionable noises inherent in priorapparatus.

The invention set forth herein is, of course, susceptible of otherembodiments and adaptations. I

The invention claimed is:

1. A radio apparatus comprisirfg an electronic valve, a carbon diskresistor connected in circuit therewith to adjust and control the actionthereof, a low tension spring proportioned to vary a low pressure uponsaid resistor and therebycause a gradual and steadyvariation inresistance through a wide working range to obtain a smooth and regularvariation in the action of said valve, and an adjustable actuator foroperating said spring.

2. A radio apparatus comprising an electronic valve, a carbon diskresistor connected in circuit therewith to control the action thereof, alow tension spring proportioned to vary a low pressure upon saidresistor and thereby cause a gradual and steady variation in resistancethrough a wide working range to obtain a smooth and regular. variationin the action of said valve, and a screw actuator for operating saidspring.

3. A radio apparatus comprising an electronic valve, two carbon diskresistors connected in circuit therewith to control the action thereof,a low tension spring proportioned to vary a low pressure upon saidresistors and thereby produce a gradual and steady variation'inresistance through a wide workmg range to obtain a smooth and regularvariation in the action of said valve, and

an adjustable actuator for operating said spring.

4. radio apparatus comprising an electronic valve, two carbon diskresistors connected in circuit therewith to control the action thereof,a low tension spring proportioned to vary a low. pressure upon saidresistors and thereby produce a gradual and steady variationinresistan0ethrough a wide working range to obtain a smooth and regular variation inthe action of said valve, and a screw actuator for operating saidspring.

In witness whereof, I have hereunto subscribed my name.

GUSTAV O. WILMS.

